1. Field of the Invention
This invention generally relates to a method for forming a composite structural member using prestressed concrete members, and more particularly to a method which may be preferably applied to the forming of composite beams by, for example, combining reinforced concrete slabs and beams such as steel beams in a composite beam bridge.
2. Description of the Prior Art
One example of conventional composite structural members widely used includes reinforced concrete floor boards or slabs and beams such as steel beams to form a composite beam bridge. Such composite beams are arranged in such a way that a reinforced concrete slab and a beam are connected by using a connector such as a dowel, whereby both members can resist, in cooperation with each other, the load to be applied thereto. In this conventional method, in order to install reinforced concrete slabs, first the beams are erected, forms are prepared, and then concrete is filled into the forms, thereby necessitating huge manpower requirements and high costs. Besides, in this composite beam bridge, the steel beam area is subjected to a positive bending moment due to vertical loads such as the weight of the beams, dead loads of the slabs, earth covering, balustrade, and pavement, and live loads due to pedestrians and vehicles. As a result, a compressive stress is generated at the upper edge side of the beams, while a tensile stress is generated at the lower edge side. These stresses lead to damage or failure such as cracks in the composite beam bridge. In order to prevent such damage or failure, the cross section of the beams is designed with a proper allowance for such vertical loads. Accordingly, the sectional area of the beam becomes comparatively wide, and therefore the weight of the beam increases, so that the entire size of the composite beam is enlarged. This means an additional cost to the construction of a bridge.